The present invention relates to methods of producing a gas developing agent for cellular concretes.
In the present state of the art a gas developing agent commonly used in the manufacture of cellular concretes is made of aluminium powder prepared by the fine particulation of pure metallic aluminium.
Such a gas developing agent, however, is an expensive and critical material, and its production is labor-consuming since aluminium granules are difficult to grind.
An attempt has been made to produce a gas developing agent from the wastes of aluminium manufacturing processes, particularly from filter cakes resulting from the production of aluminium and aluminium alloys by a thermal process.
This process consists of subjecting an aluminium-containing alloy to vacuum filtration in an ore heat-treating furnace and then reducing the aluminium. The filter cakes which are wastes from the reduction of aluminium contain from 50 to 60 percent of Al, from 4 to 5 percent of Fe, from 8 to 10 percent of Mn and other admixtures.
For producing a gas developing agent, the filter cakes are ground together with dried quartz sand to a specific particle surface size of from 5,000 to 6,000 cm.sup.2 /g (See, e.g., Inventor's Certificate of the USSR No. 149,342.
The filter cakes resulting from the vacuum filtration of aluminium and its alloys are lumps of an aluminium alloy that are difficult to grind and have a small percentage of pure aluminium.
For this reason the process of producing a gas developing agent from such material is inefficient with the resulting gas developing agent having a low activity.
In view of the fact that the quantity of filter cakes available in the above-mentioned process of vacuum filtration of aluminium is small, the process of producing a gas developing agent therefrom has found no industrial application.